Monday, July 7, 2014

Backswimmers Bite

I took my first job as a naturalist about 17 years ago. I was a summer seasonal at Tamarack Nature Center in White Bear Township, Minnesota. I learned many valuable things that summer but one of the first was a staple of the naturalist trade; Dip netting.

Take a group of kids down to a lake or pond, scoop around with nets from the shore or dock and empty the contents into kitchen tubs, cool whip containers or whatever you can find.

The exact mechanics might vary a bit from program-to-program or nature center to nature center. Sometimes we were just looking see what was there. Sometimes we would sort all the macro invertebrates we would find, putting predators in one, tub scavengers in another and decomposers in yet another. In one of my favorite versions, we would sort the animals into small tubs by species, with the kids doing all the identifying, and then tally up the results and look at population dynamics. There are many variations but in the 17 summers, springs and falls I've done dip netting there's always been backswimmers.

I learned what backswimmers are the very first time I went dip netting. They are one of the more common critters we find. They are a little less than a centimeter long, swim on their back and use long oar like legs to propel themselves through the water.

I've seen more than a few backswimmers in my life. I conservatively estimate I've done somewhere around 510 dip netting programs in the last 17 years. That works out to somewhere around 15,300 students.

I've scooped backswimmers into buckets, I move them around with spoons and screens, I've had hundreds of kids doing the same.

This weekend though, I learned. something new about backswimmers, they can bite!

Why didn't anyone ever tell me this? Does everyone else know that backswimmers can bite and I somehow missed this bit of information? How did no backswimmer ever bite one of those 15,000 school kids?

I was doing a dip netting program this weekend and wanted to show the public a little backswimmer scurrying around inside a kitchen tub placed on the dock. Some folks had arrived late at the drop-in program and I wanted to catch them up on what we'd been seeing. I used my hand to try the scoop up the little innocent looking backswimmer or maybe just make a little pool in my palm so it could swim around and people could get a good look. The backswimmer did not appreciate my hands-on pedagogical technique.

I felt a pinch on my pinky finger and quickly pulled my hand out of the water. "Ouch," I said, "I think he just bit me!"

I was quite surprised as I had absolutely no idea they could bite. I was also not ready for what happened next. Instead of the pain going away as I would expect from a tiny pinch from a tiny bug, it got worse and worse. A strong burning sensation spread through my finger as though I had been stung by a paper wasp.

I saw this as a great personal learning opportunity so here is what I have learned.

Backswimmers are in the insect order Hemiptera making them "true bugs." True bugs are those insects with piercing mouth parts. Yup, sounds right. They are in the family Notonectidae.

I'd love to tell you the genus and species of the one that bit me but there are 400 species worldwide and many can only be identified by experts examining differences in the male's genitalia under a microscope. I'll pass on that endevour.

The reason the bite hurts so much has to do with the hunting technique of the backswimmer. They catch prey with their legs and quickly pierce their skin or exoskeleton with their sharp beak. The backswimmer injects digestive enzymes and other chemicals into the animal which paralyze it and begin to dissolve the insides into goo. Once nice and juicy inside, the backswimmer can suck the prey dry. The enzymes are irritating and burn like the sting of a wasp.

So, there you go. Backswimmers have a very nasty bite. If 15,000 kids over 17 years managed to not get bitten though you must need to really tick them off to get bitten.

Must be my lucky day. So far my insides have not liquified.

About the Site:

Kirk Mona is the founder of Twin Cities Naturalist.
He is a professional naturalist and writer.

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comments:

I was always the neighborhood kid crashing through the weeds, scouring the forest, flipping logs and looking for insects, amphibians, and reptiles. Even then I wanted to know what things were. I had a few books I would have called inspiration and one was the Pond Book. A small book of some 30-50 animals (mostly insects) you'd find in a pond that came with a bucket with an air holed covered lid/scoop. To this day I still remember the Backswimmer with it's prominent "No Touch" or "Biting" warning language. I've never been bitten but I'm always wary and aware of them in the pool and elsewhere.